Abstract

In the past, geochemical research in forested watersheds has focused on understanding the basic processes that occur in soils and rocks. Watershed geochemical processes, however, are greatly influenced by, and in turn, greatly influence, both organisms and biological process in soils, and hydrologic responses of catchments. To date, geochemical research has dealt principally with basic chemical processes in soils and rocks, and much less with questions concerning hydrologic routing through catchments and the effects such routing has on temporal variation in chemical composition of surface waters.

Research on flow generation in catchments has focused on intensive field studies on plots, hillslope sections, and small catchments, with extension to larger scales necessarily involving the application of conceptual models that might (or might not) be valid. The acquisition of direct experimental evidence (for example, verifying flow generation mechanisms) on larger-scale watersheds has always been problematic. Although geochemists understand that the explanation of some geochemical observations requires that flow pathways be explicitly identified, and hydrologists understand that flow generation can be better elucidated if the geochemical history of waters is known, critical integrated communication between the disciplines is often lacking. In turn, biologists require physical and geochemical information to interpret biological effects in watersheds, and hydrologists and geochemists need to be aware of the effects of biological processes on hydrochemical response of catchments.